U.S. patent application number 14/771010 was filed with the patent office on 2016-01-21 for curable composition, transparent heat-resistant material, and use thereof.
This patent application is currently assigned to SHOWA DENKO K.K.. The applicant listed for this patent is SHOWA DENKO K.K.. Invention is credited to Hirofumi INOUE, Miyo MUKOBAYASHI.
Application Number | 20160017076 14/771010 |
Document ID | / |
Family ID | 51428312 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160017076 |
Kind Code |
A1 |
INOUE; Hirofumi ; et
al. |
January 21, 2016 |
CURABLE COMPOSITION, TRANSPARENT HEAT-RESISTANT MATERIAL, AND USE
THEREOF
Abstract
The present invention provides a curable composition, which
contains a crosslinking aid (B) containing three or more allyl
groups in the molecule in an amount of 1 to 50 parts by mass,
polyfunctional (meth)acrylic compound (C) in an amount of 5 to 50
parts by mass, and photopolymerization initiator (D1) and/or
thermal polymerization initiator (D2) in an amount of 0.1 to 10
parts by mass, respectively, as a polymerization initiator (D) to
100 parts by mass of allyl group-terminated allyl ester oligomer
(A); wherein the crosslinking aid (B) containing allyl group is a
compound containing three or more allyl groups in a molecule;
wherein the content of impurities derived from the crosslinking aid
(B) in the curable composition is less than 0.1 mass %; wherein the
content of the (meth)acrylic compound containing a hydroxyl group
in a molecule (C1) in the curable composition is 0.5 to 30 mass
%.
Inventors: |
INOUE; Hirofumi; (Tokyo,
JP) ; MUKOBAYASHI; Miyo; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHOWA DENKO K.K. |
Tokyo |
|
JP |
|
|
Assignee: |
SHOWA DENKO K.K.
Tokyo
JP
|
Family ID: |
51428312 |
Appl. No.: |
14/771010 |
Filed: |
February 27, 2014 |
PCT Filed: |
February 27, 2014 |
PCT NO: |
PCT/JP2014/054793 |
371 Date: |
August 27, 2015 |
Current U.S.
Class: |
522/64 |
Current CPC
Class: |
C08F 216/125 20130101;
C08F 222/1006 20130101; C08F 222/104 20200201; C09D 4/00
20130101 |
International
Class: |
C08F 222/10 20060101
C08F222/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2013 |
JP |
2013-039075 |
Sep 26, 2013 |
JP |
2013-199325 |
Claims
1. A curable composition, which contains a crosslinking aid (B)
containing an allyl group in an amount of 0.5 to 100 parts by mass,
polyfunctional (meth)acrylic compound (C) in an amount of 5 to 50
parts by mass, and photopolymerization initiator (D1) and/or
thermal polymerization initiator (D2) in an amount of 0.1 to 10
parts by mass, respectively, as a polymerization initiator (D) to
100 parts by mass of allyl group-terminated allyl ester oligomer
(A); wherein allyl group-terminated allyl ester oligomer has a
group represented by formula (1) as terminus ##STR00007## (in the
formula, R represents a hydrogen atom or methyl group, A.sup.1
represents one or more kinds of organic residue having an alicyclic
structure and/or an aromatic ring structure derived from
dicarboxylic acid); and contains a component comprising a structure
represented by formula (2) as a constituent unit; ##STR00008## (in
the formula, A.sup.2 represents one or more kinds of organic
residue having an alicyclic structure and/or an aromatic ring
structure derived from dicarboxylic acid, X represents one or more
kinds of organic residue derived from polyhydric alcohol, with a
proviso that X may have a branched structure through ester bonds,
having a group represented by formula (1) as terminus and a
structure represented by formula (2) as constituent unit), wherein
the crosslinking aid (B) containing allyl group is a compound
containing three or more allyl groups in a molecule; wherein the
content of impurities derived from the crosslinking aid (B) in the
curable composition is less than 0.1 mass %; wherein the
polyfunctional (meth)acrylic compound (C) includes a polyfunctional
(meth)acrylic compound containing a hydroxyl group in a molecule
(C1) and wherein the content of the (meth)acrylic compound
containing a hydroxyl group in a molecule (C1) in the curable
composition is 0.5 to 50 mass %.
2. The curable composition as claimed in claim 1, wherein the
crosslinking aid (B) is at least one member selected from triallyl
isocyanurate (TAIL) and triallyl cyanurate (TAC).
3. The curable composition as claimed in claim 1, wherein the
polyfunctional (meth)acrylic compound containing a hydroxyl group
(C1) mainly comprises (meth)acrylate monomer or oligomer containing
three or more (meth)acryloyloxy groups.
4. The curable composition as claimed in claim 1, wherein
impurities derived from the crosslinking aid (B) contain a compound
having two or less allyl groups in a molecule.
5. A transparent heat-resistant material obtained by curing the
curable composition claimed in claim 1 by irradiating light and/or
by heating.
6. An optical film, optical sheet, optical waveguide, optical lens,
optical encapsulant, optical adhesive, light guide plate, window
material or jig to prevent solder from scattering using the
transparent heat-resistant material claimed in claim 5.
7. The curable composition as claimed in claim 2, wherein the
polyfunctional (meth)acrylic compound containing a hydroxyl group
(C1) mainly comprises (meth)acrylate monomer or oligomer containing
three or more (meth)acryloyloxy groups.
Description
TECHNICAL FIELD
[0001] The present invention relates to a curable composition.
Specifically, the present invention relates to a curable
composition which is capable of obtaining an optical resin film or
sheet being excellent in heat discoloration resistance,
transparency and surface hardness; a transparent heat-resistant
material obtained by curing the composition; and the use of the
transparent heat-resistant material.
BACKGROUND ART
[0002] Conventionally, a cured product obtained by polymerizing and
curing a polyallyl ester compound containing multiple allyl ester
groups in a molecule is excellent in transparency, heat resistance,
electric properties and light resistance, and has been used for
optical materials, electronics, artificial marble, decorative
laminates and an anti-cracking agent for unsaturated polyester
resin. For example, Patent Document 1 (WO 02/33447) (EP 1331494)
and Patent Document (JP 2009-197102 A) (U.S. Pat. No. 7,989,563)
disclose an optical lens and film using a polyallyl ester compound,
Patent Document 3 (JP 2011-22490 A), Patent Document 4 (JP
2008-44357 A) (WO 2008/010588) and Patent Document 5 (JP
2007-299739 A) (WO 2007/117030) disclose a substrate using a
polyallyl ester compound, and Patent Document 6 (JP 2010-84008 A)
discloses a semiconductor device using a polyallyl ester compound
as an adhesive, respectively.
[0003] In recent years, there has been a strong demand for higher
functionality, downsizing, thinner size and reduction in weight in
electronics represented by mobile phones and thin-screen
televisions, and studies have been made on substitution of resin
members for glass members in optical materials used in the
electronics. Heat resistance and transparency near to those of
glass, and the characteristics of being lighter in weight and more
difficult to break compared to glass are required for resin used as
a substitute for glass.
[0004] Examples of resin used as a substitute for glass include
polyethylene terephthalate (PET) and polycarbonate (PC) in terms of
good mechanical strength and excellent transparency. However, the
glass transition temperature of the resin is about 70.degree. C.
and 140.degree. C., respectively, and it cannot be said that the
heat resistance of the resin is sufficient, which has limited their
usefulness.
[0005] Although the cured product obtained by polymerizing and
curing a polyallyl ester compound has higher heat resistance and
transparency compared to polyethylene terephthalate (PET) and
polycarbonate (PC), it cannot be said that the cured product has
sufficient surface hardness depending for use in a front panel of a
display unit and the like, and there has been a strong demand for a
surface hardness near to that of glass in addition to transparency
and heat resistance.
PRIOR ART
Prior Art Documents
Patent Documents
[0006] [Patent Document 1] WO 02/33447 (EP 1331494) [0007] [Patent
Document 2] JP 2009-197102 A (U.S. Pat. No. 7,989,563) [0008]
[Patent Document 3] JP 2011-22490 A [0009] [Patent Document 4] JP
2008-44357 A (WO 2008/010588) [0010] [Patent Document 5] JP
2007-299739 A (WO 2007/117030) [0011] [Patent Document 6] JP
2010-84008 A
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0012] An objective of the present invention is to provide a
curable composition which is suitable for the production of a film,
sheet or plate having a transparency required for optical
applications, high surface hardness, excellent heat resistance and
low linear expansion coefficient, obtained by curing a polyallyl
ester compound.
Means to Solve the Problem
[0013] As a result of intensive study on a curable composition
comprising a polyallyl ester compound as a polymerizable component
to solve the above problem, the present inventors have accomplished
the present invention by blending as a crosslinking aid a compound
containing a specific allyl group such as triallyl isocyanurate
(TRIC) or triallyl cyanurate (TAC) and using a polyfunctional
(meth)acrylic compound containing a hydroxyl group in
combination.
[0014] That is, the present invention relates to the curable
composition in [1] to [4] below, the transparent heat-resistant
material in [5] and the use of the transparent heat-resistant
material in [6].
[1] A curable composition, which contains a crosslinking aid (B)
containing an allyl group in an amount of 0.5 to 100 parts by mass,
polyfunctional (meth)acrylic compound (C) in an amount of 5 to 50
parts by mass, and photopolymerization initiator (D1) and/or
thermal polymerization initiator (D2) in an amount of 0.1 to 10
parts by mass, respectively, as a polymerization initiator (D) to
100 parts by mass of allyl group-terminated allyl ester oligomer
(A); wherein allyl group-terminated allyl ester oligomer has a
group represented by formula (1) as terminus
##STR00001##
(in the formula, R represents a hydrogen atom or methyl group,
A.sup.1 represents one or more kinds of organic residue having an
alicyclic structure and/or an aromatic ring structure derived from
dicarboxylic acid); and contains a component comprising a structure
represented by formula (2) as a constituent unit;
##STR00002##
(in the formula, A.sup.2 represents one or more kinds of organic
residue having an alicyclic structure and/or an aromatic ring
structure derived from dicarboxylic acid, X represents one or more
kinds of organic residue derived from polyhydric alcohol, with a
proviso that X may have a branched structure through ester bonds,
having a group represented by formula (1) as terminus and a
structure represented by formula (2) as constituent unit), wherein
the crosslinking aid (B) containing allyl group is a compound
containing three or more allyl groups in a molecule; wherein the
content of impurities derived from the crosslinking aid (B) in the
curable composition is less than 0.1 mass %; wherein the
polyfunctional (meth)acrylic compound (C) includes a polyfunctional
(meth)acrylic compound containing a hydroxyl group in a molecule
(C1) and wherein the content of the (meth)acrylic compound
containing a hydroxyl group in a molecule (C1) in the curable
composition is 0.5 to 50 mass %. [2] The curable composition as
described in [1] above, wherein the crosslinking aid (B) is at
least one member selected from triallyl isocyanurate (TRIC) and
triallyl cyanurate (TAC). [3] The curable composition as described
in [1] or [2] above, wherein the polyfunctional (meth)acrylic
compound containing a hydroxyl group (C1) mainly comprises
(meth)acrylate monomer or oligomer containing three or more
(meth)acryloyloxy groups. [4] The curable composition as described
in any one of [1] to [3] above, wherein impurities derived from the
crosslinking aid (B) contain a compound having two or less allyl
groups in a molecule. [5] A transparent heat-resistant material
obtained by curing the curable composition described in any one of
[1] to [4] above by irradiating light and/or by heating. [6] An
optical film, optical sheet, optical waveguide, optical lens,
optical encapsulant, optical adhesive, light guide plate, window
material or jig to prevent solder from scattering using the
transparent heat-resistant material described in [5] above.
Effects of the Invention
[0015] By polymerizing and curing the curable composition of the
present invention, it is possible to obtain a film or sheet
material having a transparency required for optical applications,
high surface hardness, excellent heat resistance and low linear
expansion coefficient.
MODE FOR CARRYING OUT THE INVENTION
[0016] Hereinafter, the present invention is described in
details.
[0017] The curable composition of the present invention is
characterized in containing components (A) to (D) as follows.
[0018] (A) Allyl Group-Terminated Allyl Ester Oligomer
[0019] The allyl group-terminated allyl ester oligomer (A), which
is a main component of the curable composition of the present
invention and contributes to achieving heat resistance of the cured
product, includes allyl ester oligomer which contains a group
represented by formula (1) as terminus
##STR00003##
(in the formula, R represents a hydrogen atom or methyl group,
A.sup.1 represents one or more kinds of organic residue having an
alicyclic structure and/or an aromatic ring structure derived from
dicarboxylic acid); and contains a component comprising a structure
represented by formula (2) as a constituent unit;
##STR00004##
(in the formula, A.sup.2 represents one or more kinds of organic
residue having an alicyclic structure and/or an aromatic ring
structure derived from dicarboxylic acid, X represents one or more
kinds of organic residue derived from polyhydric alcohol, with a
proviso that X may have a branched structure through ester bonds,
having a group represented by formula (1) as terminus and a
structure represented by formula (2) as constituent unit.
[0020] In the above allyl ester oligomer, there are at least two
terminuses represented by formula (1), but in a case where X in
formula (2) has a branched structure, there are three or more. In
this case, as there are multiple terminuses, there are multiple
R's. These R's do not have to be of the same kind with each other,
and the structure may include an allyl group as one terminus in
which R is a hydrogen atom and a methallyl group as another
terminus in which R is a methyl group. Moreover, all the R's do not
necessarily have to be an allyl group or a methallyl group. In an
extent that does not impair curability, some of the R's may be a
non-polymerizable group such as methyl group and ethyl group.
[0021] Similarly, with respect to the structure represented by
A.sup.1, the terminuses may be different from each other. For
example, the structure may include a benzene ring as one terminus
A.sup.1 when there is a cyclohexane ring as another terminus.
[0022] A.sup.1 and A.sup.2 in formulae (1) and (2) are one or more
kinds of organic residue having an alicyclic structure and/or an
aromatic ring structure derived from dicarboxylic acid. The portion
derived from dicarboxylic acid is shown as carbonyl structure
adjacent to A.sup.1. Therefore, A.sup.1 and A.sup.2 show a benzene
skeleton or a cyclohexane skeleton.
[0023] At least one constituent unit represented by formula (2) is
required in allyl ester oligomer. It is preferred that the
molecular weight of the whole allyl ester oligomer be increased to
a certain level by repetition of this unit, so that appropriate
viscosity may be obtained, enhancing workability and ductility of
cured product. However, when the molecular weight becomes
excessively high, it increases the molecular weight between the
crosslinking points in the cured product, which lowers glass
transition temperature (Tg) and may decrease the heat resistance.
It is critical to adjust the molecular weight appropriately
depending on the intended use.
[0024] A preferred range of the number-average molecular weight of
the allyl ester oligomer (A) measured by the GPC is from 500 to
200,000, more preferably from 1000 to 100,000.
[0025] There is no particular limitation on dicarboxylic acid from
which A.sup.1 and A.sup.2 structures are derived from. From the
viewpoint of ready availability of raw materials, terephthalic
acid, isophthalic acid, phthalic acid, 1,4-cyclohexane dicarboxylic
acid, 1,2-cyclohexane dicarboxylic acid, 1,4-naphthalene
dicarboxylic acid, 1,5-naphthalenedicarboxylic acid,
2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic
acid, diphenyl-m,m'-dicarboxylic acid, diphenyl-p,p'-dicarboxylic
acid, benzophenone-4,4'-dicarboxylic acid, p-phenylene diacetate,
p-carboxyphenyl acetate, methyl terephthalic acid and
tetrachlorophthalic acid are preferred. In view of heat resistance,
terephthalic acid, isophthalic acid, phthalic acid, 1,2-cyclohexane
dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid,
1,4-cyclohexane dicarboxylic acid, norbornene dicarboxylic acid,
bicyclodecane dicarboxylic acid, endomethylene tetrahydrophthalic
acid and methyl tetrahydrophthalic acid are more preferred. It is
desirable to use dicarboxylic acid not containing an aromatic ring
in a molecule in view of light resistance, and using
1,4-cyclohexane dicarboxylic acid is suitable for applications
requiring high transparency.
[0026] Also, in addition to dicarboxylic acid from which A.sup.1
structure is derived from, other dicarboxylic acids, which do not
contain a cyclic structure, such as maleic acid, fumaric acid,
itaconic acid, citraconic acid, endic anhydride, chlorendic
anhydride or the like may be used in combination within an extent
that does not impair the effects of the present invention.
[0027] X in formula (2) represents one or more kinds of organic
residue derived from polyhydric alcohol. A polyhydric alcohol is a
compound having two or more hydroxyl groups and X itself represents
the skeleton portion of polyhydric alcohol excluding hydroxyl
groups. Further, in the polyhydric alcohol, since at least two
hydroxyl groups have to be bonded, some hydroxyl groups may remain
unreacted when the polyhydric alcohol has a valence of three or
more. i.e. it has three or more hydroxyl groups. polyhydric alcohol
has 2 to 20 carbon atoms and preferred is polyhydric alcohol having
2 to 6 hydroxyl groups.
[0028] Among polyhydric alcohol having 2 to 20 carbon atoms,
examples of dihydric alcohol include ethylene glycol, propylene
glycol, 1,3-propane diol, 1,3-butane diol, 1,4-butane diol,
1,5-pentane diol, neopentyl glycol, hexamethylene glycol,
1,6-hexane diol, 1,4-cyclohexane dimethanol, 2-methyl-1,3-propane
diol, 3-methyl-1,5-pentane diol, diethylene glycol, dipropylene
glycol, triethylene glycol, polyethylene glycol, ethylene oxide
adduct of bisphenol A, propylene oxide adduct of bisphenol A,
hydrogenated bisphenol A,
2,2-[4-(2-hydroxyethoxy)-3,5-dibromophenyl]propane.
[0029] Examples of trihydric or higher polyhydric alcohol include
glycerin, trimethylolpropane, trimethylolethane, pentaerythritol
and dipentaerythritol. Polyhydric alcohol may be a mixture of two
or more thereof.
[0030] With respect to the constituent unit represented by formula
(2) in the allyl ester oligomer, one type of the constituent unit
may be repeated or different types of the unit may be included.
That is, the allyl ester oligomer may be a copolymer type. In this
case, in one allyl ester oligomer, several kinds of X exist. For
example, the structure may include a residue derived from propylene
glycol as one X and another residue derived from trimethylol
propane as another X. In this case, allyl ester oligomer has
branches at trimethylol propane residue. Two or more types of
A.sup.2 may exist as well. A structural formula, in a case where R
is a hydrogen atom, A.sup.1 and A.sup.2 are residues derived from
isophthalic acid, X is propylene glycol or trimethylol propane, is
shown below.
##STR00005##
[0031] [Method for Producing Allyl Ester Oligomers]
[0032] The allyl ester oligomers used in the present invention can
be produced by transesterification of allyl ester monomers of
dicarboxylic acid and polyhydric alcohol having two or more
hydroxyl groups. Allyl ester monomers of dicarboxylic acid are an
ester compound comprising dicarboxylic acid and (meth)allyl
alcohol. Specifically, examples thereof include diallyl
terephthalate, diallyl isophthalate, diallyl phthalate, diallyl
1,4-naphthalenedicarboxylate, diallyl 1,5-naphthalenedicarboxylate,
diallyl 2,6-naphthalenedicarboxylate, diallyl
2,7-naphthalenedicarboxylate, diallyl diphenyl-m,m'-dicarboxylate,
diallyl diphenyl-p,p'-dicarboxylate, diallyl
benzophenone-4,4'-dicarboxylate, diallyl p-phenylenediacetate,
diallyl p-carboxyphenylacetate, diallyl methylterephthalate,
diallyl tetrachlorophthalate, diallyl 1,2-cyclohexanedicarboxylate,
diallyl 1,3-cyclohexane dicarboxylate, diallyl 1,4-cyclohexane
dicarboxylate, diallyl norbornenedicarboxylate, diallyl
bicyclodecanedicarboxylate, diallyl
endomethylenetetrahydrophthalate, diallyl
methyltetrahydrophthalate, diallyl adipate, diallyl succinate and
diallyl maleate. Two or more of these allyl ester monomers may be
used in combination as needed.
[0033] As polyhydric alcohol, polyhydric alcohol which induces the
above-mentioned X structure is used. To obtain an allyl ester
oligomer having (meth)allyl ester group at the terminal, with
respect to the use ratio, the amount of the hydroxyl group of
polyhydric alcohol to be used needs to be less than that of the
carboxyl group of dicarboxylic acid.
[0034] As a catalyst for transesterification reaction to produce
allyl ester oligomers to be used in the present invention, a
conventionally-known transesterification reaction catalyst can be
used. Specific examples thereof include oxide and weak acid salt of
alkali metal and alkaline earth metal, and oxide and salt of weak
acid thereof; oxide, hydroxide, inorganic acid salt, alcoholate and
organic acid salt of manganese (Mn), zinc (Zn), cadmium (Cd),
zirconium (Zr), lead (Pb), titanium (Ti), cobalt (Co) and tin (Sn);
and organic tin compounds such as dibutyl tin oxide, dioctyl tin
oxide, dibutyl tin dichloride. Among these, dibutyl tin oxide and
dioctyl tin oxide are preferable.
[0035] The amount of catalyst used varies depending on the activity
of the catalyst, and a catalyst is used in such an amount that can
distil away allyl alcohol at an appropriate rate. Generally, a
catalyst is used in an amount of 0.0001 to 1 mass %, and preferably
about 0.001 to 0.5 mass % to allyl ester monomer of polycarboxylic
acid.
[0036] There is no particular limitation on the reaction
temperature in the production process, and the reaction temperature
is preferably within the range from 120 to 230.degree. C., more
preferably within the range from 140 to 200.degree. C. As an
embodiment of the reaction, it is necessary to perform the reaction
under reduced pressure or while passing the allyl alcohol generated
as a side product out of the reaction system by using an
appropriate solvent, to thereby accelerate the reaction. A specific
method for producing allyl ester oligomers is disclosed, for
example, in JP H06-74239 B.
[0037] (B) Cross-Linking Aid
[0038] The curable composition of the present invention contains
allyl group-containing crosslinking aid (B). Allyl group-containing
crosslinking aid (B) is a compound having three or more allyl
groups in a molecule, and specific examples thereof include
triallyl isocyanurate (TRIC) or triallyl cyanurate (TAC), and a
polyallyl compound in which these compounds, diallyl phthalate,
diallyl fumarate, diallyl maleate and the like are condensed. Among
these, triallyl isocyanurate (TRIC) and triallyl cyanurate (TAC)
are particularly preferable in view of crosslinking properties and
durability.
[0039] In some cases, compounds having only one or two allyl groups
are contained as impurities in the crosslinking aid. For example,
impurities contained in triallyl isocyanurate (TRIC) include
diallyl isocyanurate having two allyl groups in a molecule, allyl
isocyanurate having one allyl group in a molecule and other
isocyanurate compounds having no allyl group in a molecule.
[0040] The present inventors have confirmed that the purity of the
crosslinking aid has an effect on the heat discoloration resistance
of the transparent heat-resistant material obtained by curing the
composition. That is, it is desirable that the content of the
above-mentioned impurity components present in the curable
composition be less than 0.1 mass %. When the content of the
impurity components is 0.1 mass % or more, it reduces the heat
discoloration resistance of the transparent heat-resistant material
obtained by curing the composition by irradiating light and/or by
heating.
[0041] One kind of the crosslinking aid as component (B) may be
used singly or two or more thereof may be mixed or used in
combination. There is no particular limitation on the amount of the
crosslinking aids to be used, and the amount is 0.5 to 100 parts by
mass, preferably 1 part by mass to 50 parts by mass, to 100 parts
by mass of allyl group-terminated allyl ester oligomer (A). When
the amount of the crosslinking aids to be used is less than 0.5
parts by mass, it decreases the crosslinking degree, resulting in
insufficient surface hardness and heat resistance. When the amount
of the crosslinking aids to be used exceeds 100 parts by mass, it
makes the crosslinking degree too high, thereby resulting in
decrease in flexibility and bendability in some cases.
[0042] (C) Polyfunctional (Meth)Acrylic Compound
[0043] The curable composition of the present invention contains
polyfunctional (meth)acrylic compound (C) as being a component
contributing to attaining high surface hardness of the cured
product. In the present specification, polyfunctional (meth)acrylic
compound (C) means an organic compound having two or more
(meth)acryloyloxy groups.
[0044] In the present specification, a (meth)acrylic compound means
a methacrylic compound or an acrylic compound. Similarly,
(meth)acrylate means methacrylate or acrylate, and a
(meth)acryloyloxy group means a methacryloyloxy group or an
acryloyloxy group.
[0045] As polyfunctional (meth)acrylic compound (C), (meth)acrylate
monomer having 10 to 30 carbon atoms and having three or more
(meth)acryloyloxy groups or oligomer thereof is preferable in view
of dimensional stability, and a compound having an aliphatic or
alicyclic structure having no aromatic ring in a molecule is
preferable in view of transparency.
[0046] Specifically, examples thereof include trimethylolpropane
tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate,
pentaerythritol tetra(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, tris(2-hydroxyethyl) isocyanurate
tri(meth)acrylate, trimethylolpropane tri(meth)acrylate,
ethoxylated trimethylolpropane tri(meth)acrylate and propoxylated
trimethylolpropane tri(meth)acrylate. More preferable specific
examples include trimethylolpropane triacrylate and
dipentaerythritol hexaacrylate.
[0047] In the curable composition of the present invention,
polyfunctional (meth)acrylic compound (C) includes polyfunctional
(meth)acrylic compound having a hydroxyl group in a molecule
(C1).
[0048] Examples of polyfunctional (meth)acrylic compound having a
hydroxyl group in a molecule (C1) include pentaerythritol
tri(meth)acrylate, dipentaerythritol penta(meth)acrylate,
dipentaerythritol tetra(meth)acrylate, dipentaerythritol
tri(meth)acrylate, dipentaerythritol di(meth)acrylate and
trimethylolpropane di(meth)acrylate.
[0049] These polyfunctional (meth)acrylic compounds may be used
solely or in combination of two or more of them. The content of
polyfunctional (meth)acrylic compound having a hydroxyl group in a
molecule (C1) is preferably 0.5 to 30 mass %, more preferably 1 to
25 mass % of the curable composition. When the content is less than
0.5 mass %, it has little effect on heat discoloration resistance,
and when the content exceeds 30 mass %, it increases water
absorption.
[0050] Bifunctional (meth)acrylic compounds as below, which double
as a reactive diluent, may be used in combination:
epoxy(meth)acrylate such as dipentaerythritol di(meth)acrylate,
trimethylolpropane di(meth)acrylate, dicyclopentanyldimethylene
di(meth)acrylate,
5-ethyl-2-(2-hydroxy-1,1-dimethylethyl)-5-(hydroxymethyl)-1,3-dioxa-di(me-
th)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol
di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene
glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,
tetraethylene glycol di(meth)acrylate, triethylene glycol
di(meth)acrylate, propylene glycol di(meth)acrylate, hexanediol
di(meth)acrylate, zinc di(meth)acrylate, bisphenol A-diglycidyl
ether di(meth)acrylate, bisphenol A-ethylene oxide di(meth)acrylate
adduct, hydrogenated bisphenol A-diglycidyl ether di(meth)acrylate,
hydrogenated bisphenol A-ethylene oxide di(meth)acrylate adduct,
bisphenol F-diglycidyl ether di(meth)acrylate, bisphenol F-ethylene
oxide di(meth)acrylate adduct, hydrogenated bisphenol F-diglycidyl
ether di(meth)acrylate, hydrogenated bisphenol F-ethylene oxide
di(meth)acrylate adduct, neopentyl glycol diglycidyl ether
di(meth)acrylate, 1,6-hexanediol diglycidyl ether di(meth)acrylate;
polyester di(meth)acrylate obtained by esterification of polyhydric
alcohol, polyvalent carboxylic acid and/or anhydride thereof and
(meth)acrylic acid; and urethane di(meth)acrylate obtained by
reacting polyhydric alcohol, polyvalent isocyanate, and hydroxyl
group-containing (meth)acrylate.
[0051] The amount of polyfunctional (meth)acrylic compound to be
used as being component (C) is 5 to 50 parts by mass to 100 parts
by mass of allyl group-terminated allyl ester oligomer (A). When
the amount of the compound to be used is less than 5 parts by mass,
it results in insufficient surface hardness and heat resistance,
and when the amount exceeds 50 parts by mass, it reduces
flexibility and bendability.
[0052] (D) Polymerization Initiator
[0053] The curable composition of the present invention contains
polymerization initiator (D) to obtain a cured product. As a
polymerization initiator, either of photopolymerization initiator
(D1) and thermal polymerization initiator (D2) may be used solely,
or both of them may be used in combination.
[0054] As a photopolymerization initiator (D1), known photocleavage
type and/or hydrogen-abstraction type initiators, which are readily
cleavable by known ultraviolet irradiation to thereby generate two
radicals, may be used. These initiators may be mixed to be used.
Examples of the initiator include benzophenones such as
benzophenone, benzoylbenzoic acid, 4-phenylbenzophenone,
hydroxybenzophenone, 4,4'-bis(diethylamino)benzophenone; benzoin
alkyl ethers such as benzoin, benzoinethylether,
benzoinisopropylether, benzoinbutylether and benzoinisobutylether;
acetophenones such as 4-phenoxydichloroacetophenone,
4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone,
diethoxyacetophenone and
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1;
thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methyl
thioxanthone and 2,4-dimethyl thioxanthone;
alkyl anthraquinones such as ethyl anthraquinone and butyl
anthraquinone; benzyldimethylketals such as
2,2-dimethoxy-1,2-diphenylethane-1-one; .alpha.-aminoketones such
as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one and
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; and
.alpha.-hydroxyketones such as
2-hydroxy-2-methyl-1-phenyl-propane-1-one,
1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-propane-1-one; and
9,10-phenanthrenequinone. These initiators may be used solely or a
mixture of two or more thereof may be used.
[0055] The blending quantity of the photopolymerization initiator
is 0.1 to 10 parts by mass based on 100 parts by mass of allyl
group-terminated allyl ester oligomer (A). When the blending
quantity is less than 0.1 parts by mass, it results in insufficient
photocuring capability, and when the blending quantity exceeds 10
parts by mass, it decreases solvent resistance and flexibility, and
is not desirable.
[0056] In the case of polymerizing and curing the composition by
ultraviolet irradiation using a photopolymerization initiator, a
photosensitizer may be used in combination as needed to improve the
polymerization rate. Examples of the photosensitizer used for such
a purpose include pyrene, perylene, 2,4-diethyl thioxanthone,
2,4-dimethyl thioxanthone, 2,4-dichloro thioxanthone and
phenothiazine. The blending quantity in the case of using a
photosensitizer in combination is preferably in the range of 0.1 to
100 parts by mass based on 100 parts by mass of the
photopolymerization initiator.
[0057] A known organic peroxide and azo compound can be used as
thermal polymerization initiator (D2). Examples of organic peroxide
include diacyl peroxides such as dibenzoyl peroxide and lauroyl
peroxide; dialkyl peroxides such as di-t-butyl peroxide and dicumyl
peroxide; peroxy esters such as t-butylperoxy-benzoate,
t-butylperoxy-2-ethylhexanoate and t-hexylperoxy isopropyl
monocarbonate; ketone peroxides such as methylethyl ketone peroxide
and cyclohexanone peroxide; peroxydicarbonates such as
bis(4-t-butylcyclohexyl)peroxydicarbonate and diisopropylperoxy
dicarbonate; peroxymonocarbonates such as t-butylperoxy isopropyl
carbonate; peroxyketals such as
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane and
2,2-bis(t-butylperoxy)octane; and mixtures of two or more thereof.
Among these, peroxyester organic peroxides are preferred.
[0058] Examples of azo compounds include
2,2'-azobisisobutyronitrile, 2,2'-azobisisovaleronitrile and
dimethyl 2,2'-azobisisobutyrate.
[0059] These thermal polymerization initiators may be used solely
or in combination of two or more thereof. The blending quantity of
the thermal polymerization initiator is 0.1 to 10 parts by mass
based on 100 parts by mass of allyl group-terminated allyl ester
oligomer (A). When the blending quantity is less than 0.1 parts by
mass, thermal curing capability becomes insufficient in some cases,
and when the blending quantity exceeds 10 parts by mass, it
decreases solvent resistance and flexibility, and is not
desirable.
[0060] [Reactive Monomer]
[0061] In the curable composition of the present invention, a
reactive monomer (reactive diluent) may be added for such purposes
as control of the curing rate, adjustment of the viscosity
(improvement of workability), enhancement of the crosslinking
density and addition of functionalities. The reactive monomer is
not particularly limited, and various kinds thereof may be used,
and a monomer having a radical polymerizable carbon-carbon double
bond such as a vinyl group and an allyl group is preferred for
reacting with the allyl ester oligomer. Examples of such a monomer
include unsaturated fatty acid ester, aromatic vinyl compounds,
saturated fatty acid or aromatic carboxylic acid vinyl ester and
derivatives thereof, and crosslinkable polyfunctional monomers.
Among these, use of a crosslinkable polyfunctional monomer enables
controlling crosslink density of the cured product. Preferred
specific examples of the reactive monomer are described below.
[0062] Examples of unsaturated fatty acid ester include
alkyl(meth)acrylate such as methyl(meth)acrylate,
ethyl(meth)acrylate, butyl(meth)acrylate,
2-ethylhexyl(meth)acrylate, octyl(meth)acrylate,
dodecyl(meth)acrylate, octadecyl(meth)acrylate,
cyclohexyl(meth)acrylate and methylcyclohexyl(meth)acrylate;
aromatic ester of acrylic acid such as phenyl(meth)acrylate,
benzyl(meth)acrylate, 1-naphthyl(meth)acrylate,
fluorophenyl(meth)acrylate, chlorophenyl(meth)acrylate,
cyanophenyl(meth)acrylate, methoxyphenyl(meth)acrylate and
biphenyl(meth)acrylate; haloalkyl(meth)acrylate such as
fluoromethyl(meth)acrylate and chloromethyl(meth)acrylate; and
glycidyl(meth)acrylate, alkylamino(meth)acrylate, and
.alpha.-cyanoacrylate ester.
[0063] Examples of aromatic vinyl compounds include styrene,
.alpha.-methylstyrene, chlorostyrene, styrenesulfonic acid,
4-hydroxystyrene and vinyltoluene.
[0064] Examples of vinyl ester of saturated fatty acid or aromatic
vinyl ester carboxylate and derivatives thereof include vinyl
acetate, vinyl propionate and vinyl benzoate.
[0065] Examples of crosslinkable polyfunctional monomers include
di(meth)acrylate such as ethylene glycol di(meth)acrylate,
diethylene glycol di(meth)acrylate, triethylene glycol
di(meth)acrylate, tetraethylene glycol di(meth)acrylate,
tripropylene glycol di(meth)acrylate, 1,3-butylene glycol
di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol
di(meth)acrylate, oligoester di(meth)acrylate, polybutadiene
di(meth)acrylate, 2,2-bis(4-(meth)acryloyloxyphenyl)propane,
2,2-bis(4-(.omega.-(meth)acryloyloxypolyethoxy)phenyl)propane;
[0066] aromatic diallyl carboxylate such as diallyl phthalate,
diallyl isophthalate, dimethallyl isophthalate, diallyl
terephthalate, triallyl trimellitate, diallyl
2,6-naphthalenedicarboxylate, diallyl 1,5-naphthalanedicarboxylate,
allyl 1,4-xylenedicarboxylate and diallyl
4,4'-diphenyldicarboxylate; bifunctional crosslinking monomers such
as diallyl 1,4-cyclohexanedicarboxylate, diallyl
1,2-cyclohexanedicarboxylate, diallyl 1,3-cyclohexanedicarboxylate
and divinyl benzene; trifunctional crosslinking monomers such as
trimethylolethane tri(meth)acrylate, trimethylolpropane
tri(meth)acrylate, pentaerythritol tri(meth)acrylate,
tri(meth)allyl isocyanurate, tri(meth)allyl cyanurate, triallyl
trimellitate and diallyl chlorendate; and a tetrafunctional or
higher polyfunctional acrylate such as pentaerythritol
tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate,
dipentaerythritol penta(meth)acrylate and dipentaerythritol
hexa(meth)acrylate,
[0067] Also, bifunctional (meth)acrylic compounds as below, which
double as a reactive diluent, may be used in combination: epoxy
acrylate such as dipentaerythritol di(meth)acrylate,
trimethylolpropane di(meth)acrylate, dicyclopentanyldimethylene
diacrylate,
5-ethyl-2-(2-hydroxy-1,1-dimethylethyl)-5-(hydroxymethyl)-1,3-dioxa-diacr-
ylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate,
1,3-butanediol diacrylate, 1,4-butanediol diacrylate, ethylene
glycol di(meth)acrylate, diethylene glycol diacrylate, polyethylene
glycol diacrylate, tetraethylene glycol diacrylate, triethylene
glycol diacrylate, propylene glycol di(meth)acrylate, hexanediol
di(meth)acrylate, zinc diacrylate, bisphenol A-diglycidyl ether
diacrylate, bisphenol A-ethylene oxide diacrylate adduct,
hydrogenated bisphenol A-diglycidyl ether diacrylate, hydrogenated
bisphenol A-ethylene oxide diacrylate adduct, bisphenol
F-diglycidyl ether diacrylate, bisphenol F-ethylene oxide
diacrylate adduct, hydrogenated bisphenol F-diglycidyl ether
diacrylate, hydrogenated bisphenol F-ethylene oxide diacrylate
adduct, neopentyl glycol diglycidyl ether diacrylate,
1,6-hexanediol diglycidyl ether diacrylate; polyester diacrylate
obtained by esterification of polyhydric alcohol, polyvalent
carboxylic acid and/or anhydride thereof and acrylic acid; and
urethane diacrylate obtained by reacting polyhydric alcohol,
polyvalent isocyanate, and hydroxyl group-containing acrylate.
[0068] The above-mentioned reactive monomers can be used solely or
in combination of two or more of them. There is no particular
limitation on the blending quantity of these reactive monomers and
the blending quantity is preferably 1 to 1,000 parts by mass, more
preferably 2 to 500 parts by mass, and still more preferably 5 to
100 parts by mass, based on 100 parts by mass of allyl ester
oligomer (A). When the blending quantity is less than 1 part by
mass, it is insufficient to obtain an effect of lowering the
viscosity and the like. When the blending quantity exceeds 1,000
parts by mass, the excellent transparency of allyl ester resin may
not be exhibited, and the mechanical strength inherent to allyl
ester resin may be decreased in some cases. When a polyfunctional
monomer is used as a reactive monomer, it leads to a lower
crosslink density and insufficient heat resistance in some cases.
Therefore, it is desirable to adjust the kind and blending quantity
of the polyfunctional monomer depending on the required
heat-resistance level.
[0069] [Radically-Reactive Resin Component]
[0070] The curable composition used in the present invention may
contain a radically-reactive resin component in order to improve
various physical properties. Examples of radically-reactive resin
component include unsaturated polyester resin and vinyl ester
resin.
[0071] Unsaturated polyester resin is a condensed product of
esterification reaction of polyhydric alcohol and unsaturated
polybasic acid (and saturated polybasic acid as needed), which is
dissolved in a polymerizable unsaturated compound such as styrene
as needed. Examples thereof include resins described at pages 16 to
18 and 29 to 37 of "Polyester Resin Handbook", The Nikkan Kogyo
Shimbun Ltd., 1988. The unsaturated polyester resin can be produced
by a known method.
[0072] The vinyl ester resin is also referred to as
epoxy(meth)acrylate, and generally indicates a resin having a
polymerizable unsaturated group, which is synthesized by a
ring-opening reaction between a compound having an epoxy group
represented by epoxy resin and a carboxyl group of a carboxyl
compound having a polymerizable unsaturated group such as
(meth)acrylic acid, or resin having a polymerizable unsaturated
group, which is synthesized by a ring-opening reaction between a
compound having a carboxyl group and an epoxy group of a
polymerizable unsaturated compound having an epoxy group in a
molecule, such as glycidyl(meth)acrylate. The details are described
in "Polyester Resin Handbook", The Nikkan Kogyo Shimbun Ltd., 1988,
pages 336-357 and the like. The epoxy(meth)acrylate can be produced
by a known method.
[0073] Examples of epoxy resin serving as a raw material of vinyl
ester resin include bisphenol A diglycidyl ether and high molecular
weight homologues thereof, glycidyl ether of bisphenol A alkylene
oxide adduct, bisphenol F diglycidyl ether and high molecular
weight homologues thereof, glycidyl ether of bisphenol F alkylene
oxide adduct, and novolak polyglycidyl ethers.
[0074] The above-mentioned radically-reactive resin component can
be used solely or in combination of two or more of them. There is
no particular limitation on the blending quantity of these
radically-reactive resin components and the blending quantity is
preferably 1 to 1,000 parts by mass, more preferably 2 to 500 parts
by mass, and still more preferably 5 to 100 parts by mass, based on
100 parts by mass of allyl ester oligomer (A). When the blending
quantity is less than 1 part by mass, it has little effect of
improving the mechanical strength inherent to the
radically-reactive resin component, and leads to decrease in
workability and moldability in some cases. When the blending
quantity exceeds 1,000 parts by mass, heat resistance inherent to
allyl ester resin may not be exhibited.
[0075] The curable composition of the present invention may use
various known additives such as ultraviolet absorbing agents,
antioxidants, releasing agents, lubricants, colorants, a flame
retarder, inorganic filers, organic fillers, polymerization
inhibitors, thickeners, defoaming agents, leveling agents,
adhesion-imparting agents in order to improve hardness, strength,
moldability, durability and water resistance as long as the effects
of the invention are not impaired. Particularly, additives that do
not impede the light transmission are preferred.
[0076] Specific examples of ultraviolet absorbing agents include
triazoles such as 2-(2'-hydroxy-tert-butylphenyl)benzotriazole,
benzophenones such as 2,4-dihydroxybenzophenone, and salicylates
such as 4-tert-butylphenyl salicylate.
[0077] The blending ratio of the ultraviolet absorbing agent varies
depending on the kinds and amounts of the other ingredients, and
generally it is preferred that the amount be 0.01 to 2 parts by
mass based on 100 parts by mass of the total amount of radically
polymerizable components in the curable composition of the present
invention, more preferably 0.03 to 1.7 parts by mass and most
preferably 0.05 to 1.4 parts by mass. When the amount of the
ultraviolet absorbing agent is less than 0.01 parts by mass, a
desired effect cannot be achieved, while the amount exceeding 2
parts by mass is undesirable in consideration for the cost.
[0078] Examples of the antioxidants include phenol antioxidants
such as 2,6-di-tert-butyl-4-methylphenol,
tetrakis-[methylene-3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate]met-
hane, sulfur antioxidants such as dilauryl-3,3'-thiodipropionate,
phosphorous antioxidants such as tris nonylphenyl phosphite, and
hindered amines such as
bis-(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.
[0079] The blending ratio of the antioxidant varies depending on
the kinds and amounts of the other ingredients, and generally it is
preferred that the amount be 0.01 to 5 parts by mass based on 100
parts by mass of the total amount of radically polymerizable
components in the curable composition of the present invention,
more preferably 0.05 to 4 parts by mass and most preferably 1 to 3
parts by mass. When the amount of the antioxidant is less than 0.01
parts by mass, a desired effect cannot be achieved, while the
amount exceeding 5 parts by mass is undesirable in consideration
for the cost.
[0080] Examples of the releasing agent include stearic acid, butyl
stearate, zinc stearate, amide stearate, fluorine compounds and
silicone compounds. The blending ratio of the releasing agent
varies depending on the kinds and amounts of the other ingredients,
and generally it is preferred that the amount be 0.01 to 2 parts by
mass based on 100 parts by mass of the total amount of radically
polymerizable components in the curable composition of the present
invention, more preferably 0.03 to 1.7 parts by mass and most
preferably 0.05 to 1.4 parts by mass. When the amount of the
releasing agent is less than 0.01 parts by mass, a desired effect
cannot be achieved, while the amount exceeding 2 parts by mass is
undesirable in consideration for the cost.
[0081] The lubricant is not particularly limited, and products that
are ordinarily used may be used. Among these, a metallic soap
lubricant, a fatty acid ester lubricant, an aliphatic hydrocarbon
lubricant and the like are preferred, and a metallic soap lubricant
is particularly preferred. Examples of the metallic soap lubricant
include barium stearate, calcium stearate, zinc stearate, barium
stearate, magnesium stearate and aluminum stearate. These may be
used as a composite.
[0082] Examples of the colorants include organic pigments such as
anthraquinone pigment, azo pigment, carbonium pigment, quinoline
pigment, quinoneimine pigment, indigoid pigment and phthalocyanine
pigment; and organic dyes such as azoic dye and sulfide dye; and
inorganic pigments such as titanium yellow, iron oxide yellow, zinc
yellow, chromium orange, molybdenum red, cobalt purple, cobalt
blue, cobalt green, chromium oxide, titanium oxide, zinc sulfide
and carbon black. The blending ratio of the colorant is not
particularly limited.
[0083] Examples of the flame retarders include bromine-containing
compounds such as brominated epoxy compounds, acid-modified
brominated epoxy compounds, acryloyl group-containing brominated
epoxy compounds and acryloyl group-containing acid-modified
brominated epoxy compounds; inorganic flame retarders such as red
phosphorus, tin oxide, antimony compounds, zirconium hydroxide,
barium metaborate, aluminum hydroxide and magnesium hydroxide; and
phosphorus compound such as ammonium phosphate compounds, phosphate
compounds, aromatic condensed phosphate esters, halogen-containing
condensed phosphate esters, nitrogen-containing phosphorus
compounds and phosphazene compounds.
[0084] The blending ratio of the flame retarder varies depending on
the kinds and amounts of the other ingredients, and generally it is
preferred that the amount be 10 to 50 parts by mass based on 100
parts by mass of the total amount of radically polymerizable
components in the composition for an optical material. When the
amount of the flame retarder is less than 10 parts by mass, a
sufficient flame retardant effect cannot be expected. When the
amount exceeds 50 parts by mass, it reduces the transparency of the
cured product and is not desirable.
[0085] Examples of the inorganic filler include barium sulfate,
barium titanate, silicon oxide powder, finely-powdered silicon
oxide, crystalline silica, amorphous silica, talc, clay, magnesium
carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide,
mica powder, glass beads, glass fiber and carbon fiber. Examples of
the organic filler include acrylic resin, melamine resin, styrene
resin, silicone resin, silicone rubber and fluorine resin. These
inorganic and organic fillers can be used solely or in combination
of two or more thereof. The fillers can be added within a scope
which does not depart from the scope of the present invention: i.e.
in an amount of 1 to 50 parts by mass based on 100 parts by mass of
the total amount of radically polymerizable components in the
curable composition of the present invention.
[0086] Furthermore, the following additives may be added within a
scope which does not depart from the scope of the present
invention: polymerization inhibitors such as hydroquinone,
hydroquinone monomethyl ether, t-butyl catechol, pyrogallol and
phenothiazine; thickeners such as silica, asbestos, Orben, Benton
and montmorillonite; silicone-based, fluorine-based, acrylic or
polymer defoaming agents and/or leveling agents; and
adhesion-imparting agents such as imidazole-based, thiazole-based,
or triazole-based silane coupling agent.
[0087] These additives are not limited to the examples and any kind
of additives may be added within a scope which does not depart from
the scope of the present invention.
[0088] In addition, in the method of curing the curable composition
according to the present invention, solvent may be used if
reduction in viscosity is necessary. Examples of solvent usable for
adjusting viscosity include aromatic hydrocarbons such as toluene
and xylene, esters of acetic acid such as methyl acetate, ethyl
acetate, propyl acetate and butyl acetate, ketones such as acetone,
methyl ethyl ketone and methyl isobutyl ketone, ethers such as
tetrahydrofuran and 1,4-dioxane and alcohols such as ethyl alcohol,
n-propyl alcohol, isopropyl alcohol and butyl alcohol. However,
considering that a step of removing solvent is required at a later
stage in a case solvent is used, it is preferred that viscosity be
adjusted by using component (C) (polyfunctional (meth)acrylic
compound) which can also be used as a reactive viscosity
modifier.
[0089] A film or sheet and a molded body material being excellent
in transparency and heat resistance can be obtained by curing the
curable composition of the present invention by irradiating light
and/or by heating.
[0090] Here, an article having a thickness of less than 250 .mu.m
is referred to as a film, an article having a thickness of 250
.mu.m or more is referred to as a sheet.
[0091] In producing an optical resin film and a sheet from the
curable composition of the present invention, any curing method may
be employed as long as a certain surface hardness can be obtained.
In order to obtain a surface hardness above a certain level, it is
desirable to employ a light curing method and a thermal curing
method, or a thermal curing method only, after applying the curable
composition to be in the shape of a film.
[0092] There is no particular limitation to the conditions for
curing the curable composition, but it is suitable to apply and
cast the composition onto a transparent plastic film such as PET
(polyethylene terephthalate) and PEN (polyethylene naphthalate), a
metal sheet or a glass plate, followed by light curing and thermal
curing, or thermal curing.
[0093] In the case of light curing, the ultraviolet irradiation
method is general and, for example, it is possible to generate an
ultraviolet light using an ultraviolet lamp and irradiate the
composition with the light. Examples of the ultraviolet lamp
include a metal halide lamp, high-pressure mercury lamp,
low-pressure mercury lamp, a pulse-type xenon lamp, a mixed lamp of
xenon/mercury, a low-pressure bactericidal lamp, an electrodeless
lamp and an LED lamp, and any of them may be used. Among these
ultraviolet lamps, preferred is a metal halide lamp or a
high-pressure mercury lamp. The irradiation conditions vary
according to the kind of the lamp, but the irradiation exposure is
preferably about 20 to 5,000 mJ/cm.sup.2. Also, it is desirable to
provide the ultraviolet lamp with an ecliptic, parabolic, or
diffusional reflector and with a heat shield filter as
countermeasures against heat. Also, the curable composition may be
heated to 30 to 80.degree. C. in advance and irradiated with an
ultraviolet light in order to accelerate curing.
[0094] In the case of thermal curing, the heating method is not
particularly limited and, for example, preferred is a heating
method being excellent in terms of heating uniformity, such as the
heating by using a hot-air oven and a far-infrared oven. The curing
temperature is about 100 to 200.degree. C., preferably 120 to
180.degree. C. The curing time varies depending on the curing
method, and preferably 0.5 to 5 hours in the case of using a
hot-air oven and 0.5 to 60 minutes in the case of using a
far-infrared oven.
[0095] Since the ultraviolet cure using a photopolymerization
initiator and the thermal cure using an organic peroxide and an azo
compound are radical reaction, they are vulnerable to reaction
inhibition due to oxygen. In order to prevent the inhibition by
oxygen during the curing reaction, it is desirable to provide a
transparent cover film over the curable composition after applying
and casting the curable composition onto a transparent plastic
film, a metal sheet or a glass plate, so as to control the oxygen
concentration on the surface of the cast curable composition 1% or
less. It is necessary to use a transparent cover film that has no
pores on the surface, has a low oxygen permeability, and can stand
the heat generated at the time of ultraviolet cure and thermal
cure. For example, the film may be exemplified by films based on
PET (polyethylene terephthalate), PEN (polyethylene naphthalate),
PC (polycarbonate), PP (polypropylene), acetate resin, acrylic
resin, vinyl fluoride, polyamide, polyarylate, polyethersulfone,
cycloolefin polymer (norbornene resin) and the like may be used
solely or in combination of two or more thereof. It should be noted
that since the transparent cover film needs to be easily peeled off
from the cured product, the film may be subjected to the
easy-peeling treatment such as applying silicone resin or fluorine
resin on the surface of these cover films.
[0096] Since the curable composition of the present invention is in
the form of a liquid, it can be applied so as to obtain a certain
shape and form using a known coating applicator. Examples of the
coating method include gravure coating, roll coating, reverse
coating, knife coating, die coating, lip coating, doctor coating,
extrusion coating, slide coating, wire bar coating, curtain coating
and spin coating. By using a known forming method such as cast
molding method and photo fabrication, the composition can be formed
into an optical lens, light guide plate, window material or jig to
prevent solder from scattering. The range of the viscosity of the
curable composition at the time of application, coating and forming
is preferably within a range of from 100 to 100,000 mPas at
ordinary temperatures.
[0097] In order to impart functionality to the film, sheet or
formed body obtained by curing the curable composition of the
present invention by irradiating light and/or by heating, they may
be subjected to the surface treatment (secondary processing) such
as hard coating, antifouling coating, antireflection coating,
conductive coating and gas barrier coating. The film, sheet and
formed body may also laminated with other members using an optical
adhesive, UV adhesive and optical transparent double-sided tape.
Here, the other members indicate a transparent film or sheet made
of glass, PET (polyethylene terephthalate), PEN (polyethylene
naphthalate), PMMA (acrylic resin), PC (polycarbonate) and
cycloolefin polymers, or may be a laminate of two or more kinds of
different materials.
EXAMPLES
[0098] The present invention is to be described in more details
referring to Examples and Comparative Examples, but the present
invention will not be limited thereto.
[0099] Various properties of the cured film obtained in Examples 1
to 4 and Comparative Examples 1 to 4 and characteristics of the
used materials were evaluated by the methods as described
below.
[0100] [Pencil Hardness]
[0101] The pencil hardness was measured in accordance with JIS
K5600-5-4 by tilting the pencil lead sharpened in a cylindrical
shape at an angle of 45.degree. against the film, scratching the
surface of the product to be measured for about 5 mm under a load
of 750 g, and observing the presence or absence of a scratch. The
maximum hardness of the pencil which did not make a scratch was
measured as an index of the surface hardness.
[0102] [Measurement of Coefficient of Linear Thermal Expansion]
[0103] The coefficient of linear thermal expansion was measured
with TMA/SS6100, produced by SII NanoTechnology Inc., in a tensile
mode. A test piece in a film form had a thickness of 200
.mu.m.times.4 mm.times.40 mm (chuck distance: 20 mm) and was
applied with a tension of 30 mN, the temperature of which was
increased to 200.degree. C. at a temperature increasing rate of
5.degree. C. per minute in an atmosphere containing 100 ml/min of
nitrogen. The average coefficient of linear thermal expansion in
the plane direction within a range of from 50 to 150.degree. C. was
determined (unit: ppm/K).
[0104] [Total Light Transmittance]
[0105] The total light transmittance was measured with a test
sample having a thickness of 0.1 mm as an index of optical property
in accordance with JIS K7361-1 using NDH-2000 manufactured by
NIPPON DENSHOKU INDUSTRIES CO., LTD. In the present specification,
"highly transparent" means to have a total light transmittance of
85% or higher.
[0106] [Heat Discoloration Resistance]
[0107] The cured film was subjected to thermal treatment at
220.degree. C. for two hours using a circulating hot air dryer, and
the change in the YI value before and after the treatment was
calculated. The YI values were measured in accordance with ASTM
E313 and using spectroscopic colorimeter SD6000 manufactured by
NIPPON DENSHOKU INDUSTRIES CO., LTD.
.DELTA.YI=(YI value of the film after the deterioration by
heat)-(YI value of the film before the deterioration by heat)
[0108] [Purity of the Crosslinking Aid]
[0109] Purity of the crosslinking aid (content of impurities
derived from the crosslinking aid) was calculated from measurement
by the gas chromatography mass spectrometry (GC-MS). The
measurement conditions are as follows. [0110] Apparatus: HP6890
(manufactured by Hewlett-Packard Company) [0111] Column: DB-1MS
(manufactured by Agilent J&W), length: 30 m, inner diameter:
0.32 mm, film thickness: 0.25 .mu.m GC conditions: carrier gas: He,
column temperature: 60.degree. C. to 320.degree. C., inlet
temperature: 300.degree. C.
[0112] [Number Average Molecular Weight of Allyl Ester
Oligomer]
[0113] The number average molecular weight was measured under the
following conditions.
[0114] Apparatus used: Gel permeation chromatography (GPC) system
SIC-48011 manufactured by SHOWA DENKO K.K.
Column: Columns for gel permeation chromatography (GPC): K-801,
K-802 and K-802.5 manufactured by SHOWA DENKO K.K. Detector:
RI-201H manufactured by SHOWA DENKO K.K. Eluant: chloroform
Measurement method: 100 .mu.l of the sample dissolved in chloroform
was introduced to the column in which the temperature is adjusted
to 40.degree. C., to thereby measure the number average molecular
weight in terms of polystyrene.
[0115] [Synthesis of Allyl Ester Oligomer (AEO)]
[0116] 1,625 g of diallyl 1,4-cyclohexanedicarboxylate, 167 g of
trimethylolpropane and 0.813 g of dibutyltin oxide were charged in
a 2-L three-necked flask equipped with distillation apparatus, and
heated under a nitrogen stream while distilling off alcohol formed
at 180.degree. C. At the time when the amount of the alcohol
distilled off was about 170 g, the reaction system was gradually
depressurized to 6.6 kPa (over about 4 hours) to accelerate the
distillation rate of alcohol. After the distillate was
substantially not generated, the reaction system was depressurized
to 0.5 kPa, and the reaction was further performed for one hour,
followed by cooling the reaction product. The reaction product thus
obtained is referred to as "allyl ester oligomer (AEO)". The number
average molecular weight determined by measuring the reaction
product by GPC was 2,100.
##STR00006##
Example 1
[0117] To 100 parts by mass of the allyl group-terminated allyl
ester oligomer (AEO) produced in the synthesis example, 33 parts by
mass of triallyl isocyanurate (TRIC, trade name: TAICROS
(registered trademark), manufactured by Evonik Degussa Japan Co.,
Ltd.) as an allyl group-containing crosslinking aid, 33 parts by
mass of pentaerythritol triacrylate and pentaerythritol
tetraacrylate (PETA, trade name: ARONIX (registered trademark)
M-306, manufactured by TOAGOSEI Co., Ltd., the content of
pentaerythritol triacrylate: 67 mass %) as a polyfunctional
(meth)acrylic compound having a hydroxyl group in a molecule, 0.8
parts by mass of diphenyl(2,4,6-trimethoxybenzoyl)phosphine oxide
(TPO, trade name: Lucirin TPO, manufactured by BASF Japan Ltd.) as
a photopolymerization initiator and 1.6 parts by mass of t-hexyl
peroxy isopropyl monocarbonate (PH-I, trade name: Perhexyl
(registered trademark) I, manufactured by NOF Corporation) as a
thermal polymerization initiator were mixed to be blended uniformly
to thereby prepare an allyl ester resin composition. As a result of
GC-MS measurement of the triallyl isocyanurate (molecular weight:
249, C.sub.12H.sub.15N.sub.3O.sub.3) (TRIC) used as a crosslinking
aid in the above formulation, impurities were not detected, and the
content of the polyfunctional (meth)acrylic compound having a
hydroxyl group in a molecule was 13.4 mass %. The curable
composition was cast onto a 0.1 mm-thick PET film and laminated
with a 0.1 mm-thick PET film. The laminated film was irradiated
with UV under conditions of a peak illuminance of 300 mW/cm.sup.2,
irradiance of 800 mJ/cm.sup.2 by a UV irradiator having a metal
halide lamp to thereby produce a UV cure laminated film.
Furthermore, after thermal curing at 160.degree. C. for one hour in
an oven under air atmosphere, the film was cooled to room
temperature. Slitting was performed at both ends of the laminated
film by a CO.sub.2 laser marker (apparatus name: VD7050,
manufactured by Commax), and by peeling the PET films on both sides
of the laminated film, a cured film having a thickness of about 0.2
mm produced by curing treatment of the curable composition was
obtained.
Example 2
[0118] A cured film was produced in the same way as in Example 1
except that as a polyfunctional (meth)acrylic compound having a
hydroxyl group in a molecule, the blending quantity of
pentaerythritol triacrylate and pentaerythritol tetraacrylate
(PETA, the content of pentaerythritol triacrylate: 67 mass %, trade
name: ARONIX (registered trademark) M-306, manufactured by TOAGOSEI
Co., Ltd.) was changed to 16 parts by mass and 16 parts by mass of
trimethylolpropane triacrylate (TMPTA, trade name: ARONIX
(registered trademark) M-309, manufactured by TOAGOSEI Co., Ltd.,
the content of trimethylolpropane diacrylate: less than 1 mass %)
was added, to thereby evaluate characteristics of the film. The
content of impurities derived from the crosslinking aid in the
present preparation was not detected, and the content of the
polyfunctional (meth)acrylic compound having a hydroxyl group in a
molecule was 6.7 mass %.
Example 3
[0119] A cured film was produced in the same way as in Example 1
except that 33 parts by mass of triallyl cyanurate (trade name:
TAC, manufactured by Kayaku Akzo Corporation) was used as an allyl
group-containing crosslinking aid, to thereby evaluate
characteristics of the film. As a result of GC-MS measurement of
the triallyl cyanurate (molecular weight: 249,
C.sub.12H.sub.15N.sub.3O.sub.3) (TAC) as a crosslinking aid used in
the present preparation, the impurity content was 0.2 mass %.
Accordingly, the impurity content in the composition was 0.05 mass
% and the content of polyfunctional (meth)acrylic compound having a
hydroxyl group in a molecule was 13.4 mass %.
Example 4
[0120] A cured film was produced in the same way as in Example 1
except that diphenyl(2,4,6-trimethoxybenzoyl)phosphine oxide (TPO,
trade name: Lucirin TPO, manufactured by BASF Japan Ltd.) as a
photopolymerization initiator and t-hexyl peroxy isopropyl
monocarbonate (PH-I, trade name: Perhexyl (registered trademark) I,
manufactured by NOF Corporation) as a thermal polymerization
initiator were used in amounts of 0.4 parts by mass and 3.3 parts
by mass, respectively, to thereby evaluate characteristics of the
film. As a result of GC-MS measurement of the triallyl isocyanurate
(molecular weight: 249, C.sub.12H.sub.15N.sub.3O.sub.3) (TRIC) as a
crosslinking aid used in the present preparation, the impurity was
not detected and the content of polyfunctional (meth)acrylic
compound having a hydroxyl group in a molecule was 13.4 mass %.
Comparative Example 1
[0121] A cured film was produced in the same way as in Example 1
except that triallyl isocyanurate (trade name: TRIC; manufactured
by Nippon Kasei Chemical Company Limited) was used as an allyl
group-containing cross linking aid, to thereby evaluate
characteristics of the film. As a result of GC-MS measurement of
the triallyl isocyanurate (molecular weight: 249,
C.sub.12H.sub.15N.sub.3O.sub.3) (TAC) as a crosslinking aid used in
the present preparation, the impurity content was 0.5 mass %.
Accordingly, the impurity content in the composition was 0.1 mass %
and the content of polyfunctional (meth)acrylic compound having a
hydroxyl group in a molecule was 13.4 mass %. As a result of GC-MS
measurement of the triallyl isocyanurate (TRIC), diallyl
isocyanurate (molecular weight: 251,
C.sub.12H.sub.17N.sub.3O.sub.3) was contained in the
impurities.
Comparative Example 2
[0122] A cured film was produced in the same way as in Example 2
except that triallyl isocyanurate (trade name: TRIC; manufactured
by Nippon Kasei Chemical Company Limited) used in Comparative
Example 1 was used as an allyl group-containing cross linking aid,
to thereby evaluate characteristics of the film. As a result of
GC-MS measurement of the triallyl isocyanurate (molecular weight:
249, C.sub.12H.sub.15N.sub.3O.sub.3) (TRIC) as a crosslinking aid
used in the present preparation, the impurity content was 0.5 mass
%. Accordingly, the impurity content in the composition was 0.1
mass % and the content of polyfunctional (meth)acrylic compound
having a hydroxyl group in a molecule was 6.7 mass %.
Comparative Example 3
[0123] A cured film was used in the same way as in Example 1 except
that trimethylolpropane triacrylate (TMPTA, trade name: ARONIX
M-309, manufactured by TOAGOSEI Co., Ltd., the content of
trimethylolpropane diacrylate: less than 1 mass %) was used instead
of PETA as a polyfunctional (meth)acrylate compound having a
hydroxyl group in a molecule, to thereby evaluate the
characteristics of the film. The impurities derived from the
crosslinking aid in the present preparation was below the detection
limit and the content of the polyfunctional (meth)acrylic compound
having a hydroxyl group in a molecule was less than 1 mass %.
Comparative Example 4
[0124] A cured film was used in the same way as in Comparative
Example 3 except that an allyl group-containing crosslinking aid
was not used and the amount of trimethylolpropane triacrylate
(TMPTA, trade name: ARONIX M-309, manufactured by TOAGOSEI Co.,
Ltd., the content of trimethylolpropane diacrylate: less than 1
mass %) was used in an amount of 25 parts by mass, to thereby
evaluate the characteristics of the film. The impurities derived
from the crosslinking aid in the present preparation was 0 mass %
and the content of the polyfunctional (meth)acrylic compound having
a hydroxyl group in a molecule was less than 1 mass %.
[0125] The composition of each of the curable compositions used in
the above Examples 1 to 4 and Comparative Examples 1 to 4, and the
evaluation results of the cured films thereof are shown in Table
1.
TABLE-US-00001 TABLE 1 Examples Comparative Examples 1 2 3 4 1 2 3
4 Composition AEO 100 100 100 100 100 100 100 100 (parts by mass)
TAIC 33 33 33 33 33 33 TAC 33 PETA 33 16 33 33 33 16 TMPTA 16 16 33
25 TPO 0.8 0.8 0.8 0.4 0.8 0.8 0.8 0.8 PH-I 1.6 1.6 1.6 3.3 1.6 1.6
1.6 1.6 Content of impurities Undetect- Undetect- 0.05 Undetect-
0.1 0.1 Undetect- 0 derived from crosslinking aid able able able
able (mass %) Polyfunctional (meth)acrylic 13.4 6.7 13.4 13.4 13.4
6.7 <1 <1 compound having a hydroxyl group (mass %)
Evaluation Pencil hardness 5H 5H 5H 6H 5H 5H 6H 2H Coefficient of
linear thermal 85 80 85 85 86 82 78 100 expansion (ppm/K) Total
light transmittance (%) 92 92 91 92 91 91 91 91 Heat discoloration
resistance 1.4 2.2 1.8 2.5 2.8 3.4 3.9 3.5
[0126] From the comparison of Examples 1 to 4 with Comparative
Examples 1 to 4, it can be seen that the surface hardness is
improved, coefficient of linear thermal expansion is reduced, and
heat discoloration resistance is improved without reducing the
total light transmission by blending an allyl group-containing
crosslinking aid and a polyfunctional (meth)acrylic compound having
a hydroxyl group in a molecule. Also, from the comparison between
Example 1 and Comparative Example 1 and between Example 2 and
Comparative Example 2, it can be seen that the content of
impurities derived from the crosslinking aid has a significant
effect on the heat discoloration resistance.
INDUSTRIAL APPLICABILITY
[0127] By polymerizing and curing the curable composition of the
present invention, a transparent formed body having a high surface
hardness, a low coefficient of linear thermal expansion and
excellent heat resistance, which is suitable for optical
applications, can be obtained. Hence, the curable composition is
useful for optical applications such as an optical film, optical
sheet, optical waveguide, optical lens, optical encapsulant,
optical adhesive and light guide plate, and can be used as an
optical laminate sheet for use in various electric/electronic
equipment or optical equipment such as mobile devices, household
electrical appliances and control equipment. For example, the
laminate sheet can be used for a liquid crystal display (LCD) used
for cellular phones, game instruments, mobile devices (such as
smartphones and tablet PC's), car navigation systems, digital
cameras, watches, calculators, televisions and personal computers;
and a film- or sheet-like member such as an optical film (front
panel and the like) for a touch panel, a protecting sheet for
accessories, a lens protecting sheet, a decorative film, an
anti-scattering film, a decorative anti-scattering film, a
push-button switch (or a console panel), a membrane switch, a
sensor switch and a touch-sensitive switch.
[0128] The optical film and optical sheet obtained from the curable
composition of the present invention are particularly useful as a
protection film/sheet and a decorative/anti-scattering film for a
liquid crystal display of smartphones and tablet PC's; and as a
transparent member for use in a case, a cover, a flip case and a
jacket for protecting the instrument body, due to its high surface
hardness and excellent transparency.
[0129] Also, by taking advantage of the heat resistance inherent to
allyl ester resin, the optical film/sheet can be used as a member
being exposed to high temperature and requiring transparency in a
solder reflow furnace, electric furnace, infrared-ray heating
furnace, hot air dryer and the like. For example, it can be applied
to a window member to look inside, and a jig to prevent solder from
scattering.
* * * * *